Compounds of the formula ##STR2## where the pyridine ring contains a nitro group, R.sub.1 is hydrogen, halogen, an alkyl, alkony, alkylmercapto, hydroxy or mercapto group and A is a C.sub.1 -C.sub.5 -alkylene group and R is a dialkylamino group or a piperidino, pyrrolidino, piperazino or morpholino group are known. These compounds have a stimulating action on the central nervous system, especially an analeptic effect (Ciba French Pat. No. 1,290,128). While the French patent states that the nitro group containing compounds are of particular interest it does mention compounds on page 7, left column, second formula and in Example 15, wherein the pyridine ring is free of substituents and where R is dialkylamino. There is also generic disclosure of R.sub.1 and R being defined as above in which the pyridine ring can be free of the nitro group. However, there are not disclosed any specific compounds in which R.sub.1 is other than hydrogen and in which there is a substituent other than nitro on the pyridine ring. Also when a substituent is present on the pyridine ring, e.g., nitro, it is only shown meta to the pyridine nitrogen.
There are also known compounds of the formula ##STR3## where A and R are as defined above and R.sub.1 is phenyl or phenyl substituted by halogen, alkyl, alkoxy or alkylmercapto and R.sub.2 is hydrogen, halogen, an alkyl or alkoxy group, an amino group or a nitro group. These compounds are stated to have an analgesic effect (Ciba French Pat. No. 1,273,372).